On-line Detection and Classification of Rotor and Load Defects in PMSMs based on Hall Sensor Measurements

On-line monitoring and diagnostics of permanent magnet synchronous motors (PMSM) is becoming important with the increasing demand in PMSM applications. Most of the research effort focuses on motor current signature analysis (MCSA) as it can provide remote, on-line monitoring at low cost. However, all types of defects that produce asymmetries in the PMSM rotor or load produce identical rotor rotational frequency components. This is a serious limitation when applying MCSA since it can produce false indications and degrade the sensitivity of fault detection. In this paper, the feasibility of using analog Hall sensors signals to complement MCSA for detection and classification of rotor and load related defects is investigated. It is shown that Hall sensors installed in machines for initial rotor position estimation can be used with minimal hardware modifications, to detect and classify signatures produced by the rotor and load, for cases where MCSA fails. Experimental testing performed on an IPMSM under eccentricity, local demagnetization, and load unbalance conditions show that the reliability and sensitivity of fault detection in PMSM systems can be improved at low added cost.